Roy Suvam, Sengupta Supratim
Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India.
Life (Basel). 2022 Aug 13;12(8):1227. doi: 10.3390/life12081227.
The formation, growth, division and proliferation of protocells containing RNA strands is an important step in ensuring the viability of a mixed RNA-lipid world. Experiments and computer simulations indicate that RNA encapsulated inside protocells can favor the protocell, promoting its growth while protecting the system from being over-run by selfish RNA sequences. Recent work has also shown that the rolling-circle replication mechanism can be harnessed to ensure the rapid growth of RNA strands and the probabilistic emergence and proliferation of protocells with functionally diverse ribozymes. Despite these advances in our understanding of a primordial RNA-lipid world, key questions remain about the ideal environment for the formation of protocells and its role in regulating the proliferation of functionally complex protocells. The hot spring hypothesis suggests that mineral-rich regions near hot springs, subject to dry-wet cycles, provide an ideal environment for the origin of primitive protocells. We develop a computational model to study protocellular evolution in such environments that are distinguished by the occurrence of three distinct phases, a wet phase, followed by a gel phase, and subsequently by a dry phase. We determine the conditions under which protocells containing multiple types of ribozymes can evolve and proliferate in such regions. We find that diffusion in the gel phase can inhibit the proliferation of complex protocells with the extent of inhibition being most significant when a small fraction of protocells is eliminated during environmental cycling. Our work clarifies how the environment can shape the evolution and proliferation of complex protocells.
含有RNA链的原始细胞的形成、生长、分裂和增殖是确保RNA - 脂质混合世界生存能力的重要一步。实验和计算机模拟表明，包裹在原始细胞内的RNA可以促进原始细胞的生长，同时保护系统不被自私的RNA序列占据主导。最近的研究还表明，可以利用滚环复制机制来确保RNA链的快速生长以及具有功能多样核酶的原始细胞的概率性出现和增殖。尽管我们对原始RNA - 脂质世界的理解有了这些进展，但关于原始细胞形成的理想环境及其在调节功能复杂的原始细胞增殖中的作用等关键问题仍然存在。温泉假说认为，温泉附近富含矿物质且经历干湿循环的区域为原始原始细胞的起源提供了理想环境。我们开发了一个计算模型来研究在这样具有三个不同阶段（湿相，随后是凝胶相，接着是干相）的环境中的原始细胞进化。我们确定了含有多种类型核酶的原始细胞在这些区域能够进化和增殖的条件。我们发现凝胶相中的扩散可以抑制复杂原始细胞的增殖，当在环境循环过程中一小部分原始细胞被消除时，抑制程度最为显著。我们的工作阐明了环境如何塑造复杂原始细胞的进化和增殖。
